Infusion pumps for continuously providing a patient with accurately metered doses of various intravenous medications are normally connected to the commerical hospital power supply. In recent times, however, programmable record-keeping infusion pumps have been built which normally operate on AC power in conjuction with other apparatus, but which can be temporarily removed from the AC power supply, e.g. during transportation of a patient. Infusion pumps of this type are generally equipped with a microprocessor unit which governs the operation of the pump and keeps track of its performance. Operation of the pump with insufficient battery votage in these devices not only affects the accuracy of the medication delivery, but also interferes with the operation of the microprocessor in ways which can be potentially dangerous to the patient. On the other hand, it is undesirable to require nursing personnel to monitor the battery level, because battery operation most of the time is short encough to never raise problems of battery exhaustion.
It is consequently desirable to provide a battery power supply for this type of unit which allows non-emergency remedial action when the battery power runs low, yet maintains the system in at least minimal operational condition for as long as possible if no remedial action is taken.